Weakened plane joint former and seal



Sept. 30, 1969 L. WORSON WEAKENED PLANE JOINT FORMER AND SEAL Filed Jan. 24, 1966 FIG.7

INVENTOR. Le: Woesoxv BY fifinfl k i a 1 ATTORNEYS United States Patent 3,469,510 WEAKENED PLANE JOINT FORMER AND SEAL Lee Worson, Long Beach, Calif., assignor to Edoco Technical Products, Inc., Long Beach, Calif., a corporation of California Filed Jan. 24, 1966, Ser. No. 522,669 Int. Cl. E01c 11/10 US. CI. 94-18 2 Claims ABSTRACT OF THE DISCLOSURE The present invention relates generally to the field of construction, and more particularly to the forming and sealing of weakened plane joints in concrete slabs and the like.

A related weakened plane joint former and seal is described and set forth in my United States Letters Patent No. 3,023,681, issued Mar. 6, 1962.

In the construction of paved roads, airport runways, irrigation channels, water distribution canals and the like, it is conventional practice to insert elongated joint formers or strips at longitudinally spaced intervals in the uncured concrete or other paving material. The joint formers are often also inserted in longitudinally extending, transversely spaced relation if the slab is of appreciable width.

The joint formers define weakened plane joints in the concrete slab so that as the concrete cures and hardens it tends to crack or fracture along predetermined lines at each of the weakened plane joints. The character of the fractures is controlled by many factors, probably the most important of which is the configuration and structure of the joint former itself.

It is important to seal the slab fracture after it has been formed to prevent the downward flow of water through the joint. Unless such downward flow is prevented, water will accumulate beneath the slab around the joint, and as the adjacent slab sections undergo vertical movement due to the weight of vehicles, or due to differential water pressures in a canal, the water will gradually wash out the subgrade beneath the slab. In colder climates the water will also freeze and undesirably enlarge the joint and sometimes damage the adjoining slab sections.

Sealing of the weakened plane joint is eifected in various ways, the weakened plane joint of the aforementioned patent eifecting such sealing by including a water stop element as an integral portion of the joint former. As more particularly described in my issued patent, the joint former of the patent comprises an elongated, vertically extending band member having a pair of horizontally extending sealing strips integrally connected to each side of the band. The sealing strips included serrations defining longitudinal ribs which are firmly embedded when the joint former is laid in freshly deposited concrete, and becomes securely fixed in position when the concrete cures. This arrangement of sealing strips provides a satisfactory seal, but it has been found desirable to provide better control over the exact location of the fracture which Patented Sept. 30, 1969 occurs along the weakened plane joint as the concrete shrinks during curing.

More particularly, in the joint former of the issued patent, only the horizontal sealing strips tend to adhere to the concrete. The sides of the vertically oriented band or body of the former separate from the adjacent surfaces of the cracked slab sections and water tends to accumulate in these side spaces in the area above the horizontal sealing strips. That is, the fracture in the concrete tends to occur along a vertical plane passing through the tapered upper edge of the vertical band portion of the former, but upon reaching the upper edge the crack then tends to orient itself laterally and downwardly. along one or the other of the curved outer surfaces of the band portion. This undesirably defines a ledge or cantilever structure which on occasion breaks away and enlarges the fracture opening, subjecting the remaining concrete in the joint area to accelerated erosion and wear.

Accordingly, it is an object of the present invention to provide an improved joint former and seal having an elongated, vertically extending body made of laterally extensible material having a continuous cross-section across at least a portion of the body to prevent any downward passage of water through the body. In addition, the former includes means fixedly securing the sides of the body to adjacent portions of the slab so that as the concrete cures the sides of the body laterally extend and substantially all of the surface area of the sides moves with the shrinking adjacent portions of the slab to locate the slab fracture along a plane passing generally through the vertical center line of the body. The securing means also cooperate with ajacent slab portions to maintain an unbroken seal along the sides of the body to prevent any downward passage of water past the sides. That is, since the sides of the body are thus adhered to the adjacent concrete slab sections, there is no place for water to accumulate other than in the very small fracture area located above the joint former upper edge, and the fracture is constrained to occur directly through the body rather than around it.

Another object of the present invention is to provide a joint former of the aforementioned character in which the vertically oriented body of the weakened plane joint former is defined by a pair of side walls joined along at least one of their upper and lower extremities to provide an internal space which facilitates lateral extension of the body as the concrete cures.

A further object of the invention is to provide a weakened plane joint former of the aforementioned character but in which the vertically oriented body portion is made of a sponge material to facilitate lateral extension of the body as the concrete cures.

Yet another object of the invention is the provision of a weakened plane joint strip of the aforementioned character in which the securing means is constituted by an adhesive coating upon the sides of the vertically oriented body to thereby adhere the sides of the body to the adjacent slab sections.

A further object of the invention is to provide a joint former strip of the aforementioned character in which the sides of the vertically oriented body are secured to the adjacent slab sections for lateral movement therewith by means of horizontally oriented lateral extensions having gripping portions for embedment in the concrete. These horizontal extensions are made integral with the material of the vertical body and are elfective to cause substantially all of the surface area of the sides of the body to move with the shrinking concrete. For this purpose, a plurality of such horizontal extensions can be used on both sides of the body in vertically spaced relation. Alternatively, only a single horizontal extension can be used on each side of the body, provided the area of juncture with the body is sufficiently great in a vertical direction that substantially all of the area of the sides tends to move with the shrinking concrete slab portions.

A further object of the invention is the provision of a joint former of the aforementioned character in which the vertically oriented body is characterized by an upwardly divergent upper extremity having a fiat upper surface flush with the upper surface of the concrete slab, the surfaces of the divergent portions of the body being coated with adhesive for rigid securement to the concrete. With this arrangement, the fracture occurs through the centerline of the body, as previously indicated, with the important further advantage that the body extends completely to the surface of the concrete slab and no area therefore exists for the accumulation of water in the fracture.

Other objects and features of the invention will become apparent from consideration of the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view of a portion of a weakened plane joint former, according to the present invention, embedded in a typical concrete slab, only a portion of which is illustrated;

FIG. 2 is a vertical sectional view of the joint former embedded in a section of a slab of fresh or uncured concrete;

FIG. 3 is a view similar to FIG. 2, but illustrating the disposition of the joint former after the concrete has cured and fractured;

FIG. 4 is a vertical sectional view showing a second form of joint former embedded in concrete, and illustrating the disposition of the joint former after curing and fracturing of the concrete;

FIG. 5 is a vertical sectional view showing a third form of joint former embedded in concrete, and illustrating the disposition of the joint former after the concrete has cured and fractured;

FIG. 6 is a vertical sectional view showing a fourth embodiment of a joint former embedded in concrete, and illustrating the disposition of the joint former after curing and fracturing of the concrete;

FIG. 7 is a vertical sectional view showing a fifth form of joint former embedded in concrete, and illustrating the disposition of the joint former after curing and fracturing of the concrete; and

FIG. 8 is a vertical sectional view of a joint former not embodying the teachings of the present invention, but illustrating the location of a concrete fracture line along the exterior surface of one of the sides of the joint former.

Referring now to FIGURES 1 through 3, the weakened plane joint former 10 embodying the present invention is generally designated by the numeral 10. The former 10 includes an elongated, vertically extending body 12 characterized by a height greater than its thickness and less than the depth of the concrete slab 14 within which the former 10 is embedded.

The former 10 is made of laterally extensible or stretchable material such as polyvinyl chloride or similar suitable synthetic rubber or plastic material, and includes a pair of side walls 16 joined along their upper extremities to form a water stop portion 18. The opposed inner surfaces of the side walls 16 also define an internal, centrally located space 20 which, as will be seen, facilitates lateral extension of the body 12 as the concrete slab 14 cures.

For satisfactory operation, the height of the slot or space 20 should be approximately one-sixth of the depth of the slab 14.

The former 10 is fixedly secured to adjacent portions of the slab 14 by a coating of adhesive 22 so that as the concrete cures the adherence of the side walls 16 to the adjacent portions of the slab tend to laterally stretch or extend the body 12, as best illustrated in FIG. 3. Substantially all of the exterior surface area of the sides 16 moves with the shrinking adjacent concrete to locate the fracture line of the slab 14 along a vertical plane 24 passing generally through the vertical centerline of the body 12. Thus, the weakened plane joint provided by the embedded former 10 in the uncured concrete, as illustrated in FIG. 2, effects location of the fracture line through the former 10 by reason of the existence of the central space 20 and the adherence of the exterior surfaces of the sides 16 to the adjacent concrete.

In addition, the adhesive 22 acts as a water seal along the sides of the body 12 to prevent any downward passage of water past such sides. This, in conjunction with the sealing of the interior of the body 10 by the water stop portion 18, prevents any water from passing through the slab fracture past the former 10.

The adhesive 22 may be any suitable material capable of providing an adhesive bond stronger than the resistance of the body 20 to lateral extension. This is important to insure location of the fracture plane 24 inside or through the former 10 rather than along the outside surfaces of the former.

The adhesive 22 must also be capable of adhering the surfaces of the side walls 16 to wet or uncured concrete. For this purpose adhesives satisfying Federal Specification SS-S-158 or ASTM-D-l850-61T are satisfactory. Other satisfactory adhesives are manufactured by Edoco Technical Products, Inc., Long Beach, Calif., under the trademarks Redi-Seal F Code 3061 and Redi-Seal Code 3062. These latter materials are principally composed of virgin rubber, asphalt or coal tar, petroleum solvents, asbestos fillers, and plasticizers.

The former 10 can be embedded in the uncured concrete slab 14 immediately after it is laid, or it can embedded simultaneously with the pouring of the concrete around it, the adhesive 22 being applied to the former 10 as it is deposited in the concrete. One suitable form of embedding apparatus for this purpose is more particularly described in my United States Patent 3,274,906 issued Sept. 27, 1966.

After embedment of the former 10, and shrinkage of the concrete upon curing, any water 26 in the concrete fracture is prevented from passing through the center of the former 10 by the water stop portion 18. In addition, the adhesive 22 prevents water from passing downwardly past or around the sides 16 of the former 10.

Adhesion of the sides 16 to the concrete also causes the fracture 28 to occur along the vertical plane 24, thus avoiding the irregular fracture line 28 characteristic of the prior art, as shown in FIG. 8. The irregular fracture 28 undesirably defines an overhanging, ledge-like portion 29 which which is prone to fail under the weight of vehicles, in the case of highway structure, or by virtue of differential pressures and swiftly flowing water in the case of a water distribution canal. The configuration of certain prior art joint formers defines an even more pronounced overhanging, ledge-like portion, which further aggravates the problem of potential widening of the fracture 28.

Referring now to FIG. 4, there is illustrated another form of joint former 30 which is substantially identical to the former 10 except that the side walls 16 are joined at both their upper and lower extremities to provide not only the water stop portion 18 at the upper extremities of the sides 16, but also a water stop portion 32 at their lower extremities. The space 20 is thus completely sealed. The former 30 is useful to provide additional assurance that the water 26 will be prevented from passing through the former 30, such as in the case of a break, cut, or like opening in the water stop portion 18.

Referring now to FIG. 5, yet another joint former 34 is illustrated which is identical in configuration to the former 10, being secured to the adjacent concrete by adhesive, but which is different in that no central space is provided. Instead, the former 34 derives its capacity for lateral extension from the nature of the former material, which is spongy and of a closed-cell character to prevent any downward passage of water through the former 34. The spongy material is also sufiiciently resilient to stretch in a lateral direction to provide the necessary yieldability for establishing the location of the concrete fracture plane through the center line of the former 34. Various suitable spongy materials for this purpose are available in the prior art.

FIG. 6 illustrates still another former 36 according to the present invention, the former 36 being characterized by a plurality of horizontally oriented lateral extensions 38 integral with the elongated, vertically extending body 40 of the former 36. The lateral extensions 38 are arranged on both sides of the body 40 in vertical, spaced-apart relation and include thickened or widened gripping portions 42 at their ends to firmly anchor the extensions 38 in the concrete 14.

Like the body 12 of the joint former 10, the body 40 is characterized by a height greater than its thickness and less than the depth of the concrete slab 14. The former 36 is made of the same material as the former and includes a pair of side walls 44 defining an internal space 46 opening through the bottom of the body 40.

The upper extremity of the body 40 diverges laterally outwardly to form a V-shape portion 48 having a flat upper surface flush with the upper surface of the concrete slab 14. The space 46 extends into the V-shaped portion 48 and is enlarged so that the thickness of the sides 44 and the thickness of the horizontal upper wall of the former 36 are substantially uniform.

A coating of adhesive 22 adheres the V-shape surfaces of the portion 48 to the adjacent concrete, However, for the remainder of the body 40, the lateral extensions 38 provide much the same result as the adhesive 22. That is, the junctures of the extensions 38 with the body 40 are so distributed and arranged over the external surface area of the side walls 44 that substantially all of the surface area of the sides 44 moves with the shrinking adjacent portions of the slab 14 upon curing and fracturing of the slab. The existence and location of the space 46, together with the lateral movement of the side walls 44, establishes the plane of the fracture through the vertical center line of the body 40.

The V-shaped portion 48 and the adhesive 22 prevent any downward passage of water both through the body 40 and past the sides of the body 40. Moreover, the location of the V-shape portion 48 flush with the adjacent surface of the concrete slab 14 completely eliminates any area within which the water 26 can collect, thereby greatly reducing potential erosion of the fracture area.

FIG. 7 illustrates another joint former 50 according to the present invention, the former 50 being identical to the former 36 in every respect except for the character and number of lateral extensions 38.

More particularly, the former 50 includes only one lateral extension 52 integral with each of the opposite side walls 44 of the former 50. However, the area of juncture of each extension 52 with its side walls 44 extends throughout a substantial vertical portion of the side wall 44 so that substantially all of the surface area of the side walls 44 of the former 50 tends to move with the shrinking adjacent portions of the slab 14. Moreover, any slight separation which might occur between the side walls and the adjacent concrete in the area located between the V-shape portion 48 and the upper terminus of the lateral extensions 52 is of no consequence because of the sealing action provided -by the adhesive 22.

From the foregoing it will be apparent that a weakened plane joint has been provided which is operative to establish the plane of the concrete fracture directly through the body of the joint former, rather than about the exterior surface of one or the other of the sides of the body. This is accomplished by securing the sides of the former to the adjacent concrete either by means of an adhesive or by means of properly distributed or configured lateral extensions of the body so that the body side walls tend to adhere to the adjacent concrete over substantially all of their surface area whereby they move with the shrinking concrete. Such adherance also provides a water stop seal over substantially the entire surface area of the sides of the body.

Various modifications and changes may be made with regard to the foregoing detailed description without departing from the spirit of the invention or the scope of the following claims.

I claim:

1. In a concrete slab, a weakened plane expansion joint comprising:

an elongated, vertically extending and laterally extensible body characterized by a height greater than its thickness and less than the depth of said slab, said body having a continuous cross-section across at least a portion of said body to prevent downward passage of water through said body; and

means fixedly securing the sides of said body to adjacent portions of said slab whereby, as said concrete cures, said sides of said body tend to move laterally away from each other with the shrinking adjacent portions of said slab to locate the fracturing of said slab along a plane passing generally through the vertical centerline of said body said means including an adhesive coating upon at least the upper portions of said sides of said body and cooperating with said adjacent portions of said slab to maintain an unbroken seal along said upper portions of said sides of said body to prevent downward passage of Water past said sides, said means further including lateral extensions integral with said body and having gripping portions embedded in said concrete, the areas of juncture between said extensions and said body being distributed and arranged such that substantially all of the surface area of the sides of said body moves with the shrinking adjacent portions of said slab.

2. In a concrete slab, a weakened plane joint according to claim 1 wherein a plurality of said lateral extensions are arranged in vertical, spaced apart relation on both sides of said body and integral therewith whereby substantially all of the surface area of the sides of said body moves with the shrinking adjacent portions of said slab.

References Cited UNITED STATES PATENTS 1,241,405 9/1917 Leach 94-18 2,210,138 8/ 1940 Bishop 94-182 3,023,681 3/1962 Worson 94-l8 3,179,026 4/1965 Crone i 94-182. 3,218,941 11/1965 Daum 9418 3,261,087 7/ 1966 Schlumberger 94-18 XR 3,255,680 6/1966 Cooper.

FOREIGN PATENTS 374,380 1/ 1964 Switzerland.

JACOB L. NACKENOFF, Primary Examiner 

